Antidepressants and sleep

By Dr Simon Kyle

How do antidepressants affect sleep?

Antidepressants are principally prescribed for the treatment of clinical depression. However, given the strong bi-directional relationship between depression and insomnia, several research studies have assessed the effects of antidepressants on sleep continuity (sleep onset, wake after sleep onset, total sleep time, and sleep efficiency) and sleep architecture (stages of sleep). Indeed, many clinicians will often give out off-label prescriptions of antidepressants for poor sleep, rather than sleeping pills, due to the perception that they are less habit-forming – and so can be taken for longer – and that they have less potential for side-effects. It is important to note, however, that rigorous controlled trials of antidepressants for the effective treatment of insomnia are lacking and that current guidelines do not endorse their widespread use.

The extent to which an antidepressant will affect sleep is ultimately determined by the class of antidepressant being prescribed. This will influence the resultant pharmacologic effects on brain neurotransmitters like serotonin and noradrenaline, and receptor sites including histamine, serotonin, and adrenergic receptors. It is also important to note that effects on sleep can vary between and within classes of antidepressant medications, and will depend on whether one studies healthy participants or those with clinical depression (Wilson & Argyropoulou, 2005; Mayers & Baldwin, 2005).

In general, antidepressants tend to suppress REM sleep and increase the time taken to enter REM sleep. Both increased REM sleep density and reduced latency to REM sleep are characteristic of patients with depression and thus antidepressants appear to normalize these parameters. Indeed the amount to which antidepressants suppress REM sleep has been associated with enhanced overall antidepressant response (less severe depression symptoms). In some studies, selective serotonin reuptake inhibitors (SSRIs), like sertraline and fluoxetine, have been shown to disturb/fragment sleep. Tricyclic antidepressants (TCAs), like amitryptiline, and serotonin antagonist and reuptake inhibitors (SARIs), like trazadone, have been shown to have a sedative effect, improving sleep continuity and quality. Effective antidepressant treatment response, where mood is improved, may often be accompanied by improved subjective ratings of sleep; however, recent research data also suggest that poor sleep can frequently emerge as a consequence of antidepressant treatment, remaining even after successful remission of depression.

You should always consult your doctor for advice on medication – starting, changing or finishing a course of medication can have serious effects. Ensure that you consult your GP if you have any questions on this.